FIG. 1 illustrates a conventional camera module 100 which includes an image sensor 105, a substrate 110, a lens holder 115, and a threaded lens barrel 120 that contains lens elements. Threaded lens barrel 120 includes outside threads that mate with inside threads disposed on an inside surface of lens holder 115. These threads allow threaded lens barrel 120 to be threaded in and out during the assembly process to tune or adjust the offset distance H1 between the lens elements within threaded lens barrel 120 and image sensor 105. Configuring offset distance H1 sets the focus depth and magnification of camera module 100. Since offset distance H1 is set during assembly and not adjustable during operation, camera module 100 is referred to as a fixed focus design.
While threaded lens barrel 120 provides simplified tuning during assembly along the Z-axis by rotating threaded lens barrel 120, it also adds significant bulk in the X-Y dimensions. In compact devices, such as laptops, netbooks, tablets, cell phones, and head mounted displays (“HMDs”), every millimeter of space can be significant.
FIG. 2 illustrates a wafer level camera module 200, which is fabricated using wafer replication technology. Lens elements 205 are replicated onto each of the wafers 210 and wafers 210 are then stacked on top of an image sensor wafer 215. The stacked wafers are then diced into individual camera modules. Wafer level camera module, such as camera module 200, can save significant X-Y space; however, the materials suitable for wafer level camera modules are very limited and the optical performance of lens elements 205 is generally poor. Thus the overall performance of such camera modules is poor when compared to conventional camera modules with barrel shaped lens assemblies.